The invention relates to a device for circulating a grain product. Devices of this type are used in the grain processing industry, in particular for drying and/or storing a grain product.
The moisture content of freshly harvested grain does not permit storage without the risk of spoilage. The moist grain forms hotspots which increase in size and ruin the grain. In addition, insects settle at these locations and contribute to the damage of the grain product.
For this reason, freshly harvested grain must be adequately dried before being stored, which is typically done in drying silos. The freshly harvested grain is continuously or cyclically fed into the drying silo from the top, while dry, warm air is blown into the drying silo from below. The dry air removes a certain amount of water from the grain and is vented into the ambient air from the upper region of the drying silo. The drying process can be accelerated by continuously circulating and intermixing the grain product. It is known in the art to employ a circulating unit located and operating in the upper region of the drying silo. This circulating unit is provided with a several driven feed screws arranged side-by-side, which are immersed in the deposited grain product and circulate the grain product from the bottom to the top. The feed screws reach all areas of the deposited grain product due to the revolving motion of the circulating unit and the changing radial position of the individual feed screws.
After an adequate drying process, the grain product is moved for storage into corresponding round storage silos or into low-rise storage buildings, where the grain product must be continuously aerated and/or circulated. This process is intended to prevent a formation of hotspots.
For example, DE-OS 27 21 782A discloses a corresponding circulation-storage unit for grain products for use in a round storage silo. This circulation-storage unit for the grain product is located in the center of the storage silo, is fixedly connected with the storage silo, and includes essentially a conveyor cylinder and a driven feed screw. The stored grain product slides across a conical bottom into the region of the feed screw and is transported by the feed screw through the conveyor cylinder into the upper region of the storage silo, where it is once more deposited on the already deposited grain product. This produces a revolving feed motion.
The circulation-storage unit for grain products is implemented as a fixed component of the storage silo and is therefore provided only for this particular application. The unit cannot be used in low-rise storage buildings because of its restricted effective range, which severely limits in the application of the circulation-storage unit. The costs associated with designing and manufacturing the circulation-storage unit for grain products is also quite high because it requires a conveyor cylinder.
After drying, the grain product is typically transported to large storage buildings, where it is poured out to form a flat pile. The grain is typically circulated by turning it over manually, which requires a lot of manual labor and many workers. It is also known in the art to use heavy mixing machinery for circulating the grain, which is not always available and is in addition very expensive. DE 35 00 881 A1 discloses a drilling screw for turning and loosening grain in storage filling spaces, which essentially consists of a hand drill and a feed screw clamped in the hand drill. The feed screw has a length corresponding to the height of the poured grain. The drilling screw is supported by the bottom of the silo by a sphere disposed on the tip of the feed screw. The drilling screw can be used both in round storage silos and in low-rise storage buildings. However, the drilling screw is relatively ineffective in low-rise storage buildings. Significant manual forces have to be generated to overcome the resistance of the drilling screw rotating in the grain, to hold the drilling screw in its operating position during operation and to move it from place to place. The drilling screws can therefore be operated only for short periods of time, which essentially prevents their use in low-rise storage buildings.
U.S. Pat. No. 4,491,422 discloses a similar device for circulating a grain product from a lower to an upper storage region. The device has a similar design, but includes an additional braking plate which opposes the inertial and feed forces and thus prevents the device from being immersed in the grain product.
U.S. Pat. No. 5,980,100 describes a device for treatment of a fluid, such as mixing or aerating of waste water. This device includes a feed screw and a drive unit for the feed screw. The drive unit and the feed screw are coupled to one another by a coupling unit. This device is intended for swirling the waste water in the region of the feed screw and, in a particular embodiment, introduces air at atmospheric pressure through a pipe into the water.
It is therefore an object of the invention to develop a device of this type for circulating a grain product, which can be used over an unlimited period of time and which does not require a manual force for circulation.